I am trying to get my Iwatch to notify me when my phone is left behind. The instructions I found for iOS 18. Says press crown, turn to find "find devices". The iPhone it is connected to does not show there.
[Re-Titled by Moderator]
Follow the steps in this article to set this up on your iPhone first:
Set separation alerts in case you leave a device behind in Find My on iPhone - Apple Support
After that, your iPhone should be listed in "Find Devices" on your watch. Tap on it and enable "Notify When Left Behind"
Connected iPhone not showing on Apple Watch Find My
